While we're talking reproduction...

...there's quite a long article at Aeon called "The macho sperm myth" which you might dismiss as sounding too doctrinally feminist in approach, but you shouldn't.  It mentions some things about what sperm cells get up to inside of women which I don't think I had heard of before.  For example:

The entrenched notion that human sperm, once ejaculated, engage in a frantic race to reach the egg has completely overshadowed the real story of reproduction, including evidence that many sperm do not dash towards the egg but are instead stored for many days before proceeding. It was long accepted as established fact that human sperm survive for only two days in a woman’s genital tract. However, from the mid-1970s on, mounting evidence revealed that human sperm can survive intact for at least five days. An extended period of sperm survival is now widely accepted, and it could be as long as 10 days or more.

Other myths abound. Much has been written about mucus produced by the human cervix. In so-called ‘natural’ methods of birth control, the consistency of mucus exuding from the cervix has been used as a key indicator. Close to ovulation, cervical mucus is thin and has a watery, slippery texture. But precious little has been reported regarding the association between mucus and storage of sperm in the cervix. It has been clearly established that sperm are stored in the crypts from which the mucus flows. But our knowledge of the process involved is regrettably restricted to a single study reported in 1980 by the gynaecologist Vaclav Insler and colleagues of Tel Aviv University in Israel.

In this study, 25 women bravely volunteered to be artificially inseminated on the day before scheduled surgical removal of the womb (hysterectomy). Then, Insler and his team microscopically examined sperm stored in the crypts in serial sections of the cervix. Within two hours after insemination, sperm colonised the entire length of the cervix. Crypt size was very variable, and sperm were stored mainly in the larger ones. Insler and colleagues calculated the number of crypts containing sperm and sperm density per crypt. In some women, up to 200,000 sperm were stored in the cervical crypts.

Insler and colleagues also reported that live sperm had actually been found in cervical mucus up to the ninth day after insemination. Summarising available evidence, they suggested that after insemination the cervix serves as a sperm reservoir from which viable sperm are gradually released to make their way up the oviduct. This dramatic finding has been widely cited yet largely ignored, and there has never been a follow-up study.